1. Field of the Invention
The present invention relates to a driving technique for moving a movable body using a driving force provided by a driving shaft.
2. Background of the Related Art
Some image pickup apparatus such as digital cameras include a shake compensation unit which shifts the position of an image pickup device to compensate for a shake of a hand during a shooting operation (for example, see JP-A-2006-259114 (Patent Document 1)).
In a common shake compensation unit having an image pickup device shifting mechanism, a driving force is generated by a piezoelectric actuator disposed on a side of an image pickup device to shift the image pickup device in a plane that is perpendicular to the optical axis of the device.
Specifically, the shake compensation unit includes a piezoelectric actuator having a piezoelectric element expanding and contracting according to a voltage applied thereto and a driving shaft extending from the piezoelectric element, a fixed member on which the piezoelectric actuator is provided, and a driven body (which is also referred to as “slider”) having an image pickup device provided thereon. The shake compensation unit has a mechanism formed by frictionally coupling a bearing section provided on the slider and the driving shaft of the piezoelectric actuator provided on the fixed member. In the shake compensation unit having such a mechanism, the slider is driven based on a principle that the movement of the slider synchronously follows the driving shaft when the driving shaft is relatively slowly displaced because of the force of the friction coupling and that the slider does not move when the driving shaft is relatively rapidly displaced because of a slip occurring at the friction-coupled region.